This invention relates to a transporting apparatus which takes out postal matter or like sheets or sheet-like parts sorted and stacked in a plurality of stacking boxes in a plurality of vertically arranged rows and transports the taken-out matter to a next process station.
Postal matter such as letters and postal cards which are collected in stacking boxes for different address areas, is a well-known example of matter that is sorted and stacked in stacking boxes. In the case of postal matter, stacks of sorted stacked matter in stacking boxes for different address areas are taken out and transported to a next common process section, in which an address card is put on each stack and the stack is then bundled together with the address card.
A prior art example of the transport apparatus, which handles postal matter, will now be described briefly with reference to FIGS. 1 and 2.
A sorting unit (a) comprises a number of stacking boxes. These stacking boxes are arranged in three horizontal rows, i.e., uppermost row (b), middle row (c) and lowermost row (d). Sorted postal matter (A) such as letters and postal cards is charged into corresponding stacking boxes in these rows from the front side of the boxes. The sorted postal matter (A) is periodically pushed out by a push-out mechanism (not shown) from the front side, as shown by an arrow, to be transferred onto trays, which are secured to endless conveyer belts (e, f, g) disposed in the vicinity of the back of the sorting unit (a) and corresponding to the respective rows of stacking boxes.
The conveyor belts (e, f, g) convey the trays containing the postal matter (A) transferred thereto to the end of the forward belt run. A common elevator (i) which consists of an endless transfer belt having trays secured thereto is disposed vertically behind the forward end of the conveyor belts (e, f, g). The postal matter (A) having been conveyed to the forward end is transferred to the common elevator (i), as shown by an arrow, by a pusher which is provided at the forward end of each conveyor belt. The elevator (i) brings down the postal matter (A) received from the individual conveyor belts (e, f, g) to a position at the same level as a horizontal transport line (k) which extends at a lower level than the level of the lowermost conveyor belt (g). When the postal matter (A) is brought to the lower set position, it is pushed out by a pusher (j) disposed behind the tray of the elevator (i), as shown by an arrow, to be transferred to one of trays secured to the transport line (k).
The transferred postal matter (A) is conveyed horizontally on the transport line (k), as shown by an arrow. When the postal matter (A), which is in the form of a stack, reaches an address card attaching station, (l), an address card (m) is placed on the stack. The postal matter stack is then further conveyed to reach a bundling station (n). In this station, the postal matter stack (A) is bundled together with the address card (m) attached thereto with a tape (p). The postal matter bundle (A) is then conveyed to a forward end of the line (k), where it is pushed out of the line (k) by a pusher (g), as shown by an arrow.
In the above transport system, the postal matter (A) is transferred three times from tray to tray by pushers in its course from each of the stacking boxes (b, c, d) in the sorting unit (a) to the following process stations of address card attachment and bundling. However, when the postal matter (A) stacked in a tray is transferred, it is likely to get out of the regularly stacked state. In such a case, a trouble in processing or defective processing will occur in the succeeding process stations.
For the above reason, it has desired to minimize the number of transfers of postal matter involved to thereby minimize the possibility of the postal matter getting out of the regularly stacked state.
In another aspect, on each of the conveyor belts (e, f, g) a plurality of trays are secured thereto at a fixed interval corresponding to the interval of the stacking boxes in the sorting unit (a). These trays have a considerable depth or height. After the postal matter (A) has been transferred from each tray on each of the conveyor belts (e, f, g) to the common elevator (i), the empty tray is conveyed by the lower return run of the belt back to its start position of transport as shown by dashed lines in FIG. 2. For this reason, the vertical interval of the conveyor belts (e, f, g) cannot be reduced beyond a certain limit, that is, the height dimension of each row of stacking boxes in the sorting unit (a) cannot be reduced beyond a certain limit. Therefore, if it is intended to provide a large number of vertically arranged rows of stacking boxes, the uppermost stacking box row is liable to be too high for operators to perform maintenance and inspections easily. Further, in the prior art transport apparatus as described above, the lower set position of the common elevator (i) has to be below the level of the lowermost conveyor belt (g), so that the height of the apparatus as a whole must be increased that much.
Accordingly, a construction of an apparatus, the height of which can be reduced, has been called for.
A further deficiency of the prior art transport apparatus is the fact that the conveyor belts (e, f, g) carry trays which are permanently secured to them. When the belt is elongated due to fatigue or the like in long use, an error is thus produced in the interval between the trays. As mentioned earlier, the interval of the trays must correspond to the interval of stacking boxes in the sorting unit. When an error is produced in the interval between the trays, therefore, the register between trays and stacking boxes is lost. If this results, stable operation can no longer be obtained. Moreover, when the belt is elongated, an error between the timing of feed of trays on the conveyor belts (e, f, g) and the timing of feed of trays in the elevator (i) is likely.
Accordingly, a transport apparatus which can ensure correct register between trays and stacking boxes and also correct coincidence of feeding of trays over a long period of time is desired.